Pink streak in CM 7w3d freaking out!

I went to the bathroom and saw a light pink steak in my CM. CM is very thick and creamy and, apart from the pink streak in, it normal. I had sex yesterday ummm quite vigorously. Could this have caused the pink discharge? I had stomach pains today but no real uterine cramping... At least I don't think. But now I'm freaking out that his is a start of a miscarriage. It's too late to call my doctor and I feel that if I go the the ER they will think I'm crazy. 

I had my doctors appointment last week and we saw the hearbeat. I measured about 2 days behind but I have ovulated late. 

Any advice?! I'm so scared please tell me what to do!